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The Secret Letter (Japanese: みっしょ) is an item in Densetsu no Starfy 2, found in Torrent's Waterfall (Stage 10-1). It is a scroll with information on it. Starfy has to deliver it to Ogyon's friend, Ogyan. Disclosed in the Secret Letter is information about the 'evil' Echigyoya's plans. In a flashback, Ogyon eavesdropped on a conversation between Echigyoya and Puchi Ogura #10. Later, Puchi Ogura #10 attached a small shark-like creature on to Ogyon's fin that hurts her.
Before Starfy gets to deliver it to Ogyan, Puchi Ogura #10 finds the Secret Letter and takes it away from Starfy before splitting into four slightly different versions of himself. Starfy must defeat three copies of Puchi Ogura #10 before defeating the real Puchi Ogura #10 with three Star Spins to retrieve the Secret Letter.